As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemens’ ProductCERT Security Advisories (CERT Services | Services | Siemens Global).

1. EXECUTIVE SUMMARY

CVSS v3 9.8
ATTENTION: Exploitable remotely/low attack complexity 
Vendor: Siemens 
Equipment: CPCI85 Firmware of SICAM A8000 Devices 
Vulnerability: Improper Neutralization of Special Elements used in a Command (‘Command Injection’)

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an unauthenticated remote attacker to perform arbitrary code execution. 

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following software from Siemens is affected: 

CP-8031 MASTER MODULE (6MF2803-1AA00): All versions prior to CPCI85 V05 
CP-8050 MASTER MODULE (6MF2805-0AA00): All versions prior to CPCI85 V05 

3.2 VULNERABILITY OVERVIEW

3.2.1 IMPROPER NEUTRALIZATION OF SPECIAL ELEMENTS USED IN A COMMAND (‘COMMAND INJECTION’) CWE-77 

Affected devices are vulnerable to command injection via the web server port 443/TCP if the parameter “Remote Operation” is enabled; this parameter is disabled by default. This vulnerability could allow an unauthenticated remote attacker to perform arbitrary code execution on the device. 

CVE-2023-28489 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H). 

3.3 BACKGROUND

CRITICAL INFRASTRUCTURE SECTORS: Multiple 
COUNTRIES/AREAS DEPLOYED: Worldwide 
COMPANY HEADQUARTERS LOCATION: Germany 

3.4 RESEARCHER

Steffen Robertz, Gerhard Hechenberger, Stefan Viehböck, Christian Hager, and Gorazd Jank from SEC Consult Vulnerability Lab on behalf of Netz Niederösterreich GmbH, EVN Gruppe reported this vulnerability to Siemens. 

4. MITIGATIONS

Siemens has released updates for the affected products and recommends updating to the latest versions: 

CP-8050 MASTER MODULE (6MF2805-0AA00): Update to CPCI85 V05 or later. 
CP-8031 MASTER MODULE (6MF2803-1AA00): Update to CPCI85 V05 or later. 

Siemens has identified the following specific workarounds and mitigations userscan apply to reduce the risk: 

Limit access to the web server on port 80/TCP and 443/TCP with an external firewall. 

Operators of critical power systems (e.g. TSOs or DSOs) worldwide are usually required by regulations to build resilience into the power grids by applying multi-level redundant secondary protection schemes. Siemens recommends that the operators check whether appropriate resilient protection measures are in place. The risk of cyber incidents impacting the grid’s reliability can thus be minimized by virtue of the grid design. Siemens recommends applying the provided security updates using the corresponding tooling and documented procedures made available with the product.  

Siemens recommends that operators:  

Apply provided security updates using the corresponding tooling and documented procedures made available with the product.  
Automatically apply security updates across multiple product instances. If supported by the product, operators may use an automated means to apply the security updates across multiple product instances may be used. 
Validate any security update before being applied. It is recommended to perform the update process under the supervision of trained staff in the target environment.   
Protect network access with appropriate mechanisms (e.g. firewalls, segmentation, VPN) as a general security measure. 

Recommended security guidelines can be found at the Siemens web page for Grid Security.

For more information, see the associated Siemens security advisory SSA-472454 in HTML and CSAF. 

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

CISA also provides a section for control systems security recommended practices on the ICS webpage at cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.

No known public exploits specifically target this vulnerability.